package com.tongzhou.util;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
/**
 * 
 * @author 彭定雄
 */
public class DES {

    private static final String PASSWORD_CRYPT_KEY = "#os%oss&"; 

    private final static String DES = "DES";     

    /** 

     * 加密 

     * @param src 数据源 

     * @param key 密钥，长度必须是8的倍数 

     * @return  返回加密后的数据 

     * @throws Exception 

     */ 

    public static byte[] encrypt(byte[] src, byte[] key)throws Exception { 

            //DES算法要求有一个可信任的随机数源 

            SecureRandom sr = new SecureRandom(); 

            // 从原始密匙数据创建DESKeySpec对象 

            DESKeySpec dks = new DESKeySpec(key); 

            // 创建一个密匙工厂，然后用它把DESKeySpec转换成 

            // 一个SecretKey对象 

            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES); 

            SecretKey securekey = keyFactory.generateSecret(dks); 

            // Cipher对象实际完成加密操作 

            Cipher cipher = Cipher.getInstance(DES); 

            // 用密匙初始化Cipher对象 

            cipher.init(Cipher.ENCRYPT_MODE, securekey, sr); 

            // 现在，获取数据并加密 

            // 正式执行加密操作 

            return cipher.doFinal(src); 

         } 

    

         /** 

         * 解密 

         * @param src 数据源 

         * @param key 密钥，长度必须是8的倍数 

         * @return   返回解密后的原始数据 

         * @throws Exception 

         */ 

         public static byte[] decrypt(byte[] src, byte[] key)throws Exception { 

            // DES算法要求有一个可信任的随机数源 

            SecureRandom sr = new SecureRandom(); 

            // 从原始密匙数据创建一个DESKeySpec对象 

            DESKeySpec dks = new DESKeySpec(key); 

            // 创建一个密匙工厂，然后用它把DESKeySpec对象转换成 

            // 一个SecretKey对象 

            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES); 

            SecretKey securekey = keyFactory.generateSecret(dks); 

            // Cipher对象实际完成解密操作 

            Cipher cipher = Cipher.getInstance(DES); 

            // 用密匙初始化Cipher对象 

            cipher.init(Cipher.DECRYPT_MODE, securekey, sr); 

            // 现在，获取数据并解密 

            // 正式执行解密操作 

            return cipher.doFinal(src); 

         } 

      /** 

       * 密码解密 

       * @param data 

       * @return 

       * @throws Exception 

       */ 

      public final static String decrypt(String data){ 

         try { 

          return new String(decrypt(hex2byte(data.getBytes()),

             PASSWORD_CRYPT_KEY.getBytes())); 

        }catch(Exception e) { 

        } 

        return null; 

      } 

      /** 

       * 密码加密 

       * @param password 

       * @return 

       * @throws Exception 

       */ 

      public final static String encrypt(String password){ 

        try { 

          return byte2hex(encrypt(password.getBytes(),PASSWORD_CRYPT_KEY.getBytes()));
        }catch(Exception e) { 

        } 

        return null; 

      } 

    /** 

     * 二行制转字符串 

     * @param b 

     * @return 

     */ 

      public static String byte2hex(byte[] b) { 

            String hs = ""; 

            String stmp = ""; 

            for (int n = 0; n < b.length; n++) { 

                stmp = (java.lang.Integer.toHexString(b[n] & 0XFF)); 

                if (stmp.length() == 1) 

                    hs = hs + "0" + stmp; 

                else 

                    hs = hs + stmp; 

            } 

            return hs.toUpperCase(); 

       } 

      public static byte[] hex2byte(byte[] b) { 

        if((b.length%2)!=0) 

           throw new IllegalArgumentException("长度不是偶数"); 

            byte[] b2 = new byte[b.length/2]; 

            for (int n = 0; n < b.length; n+=2) { 

              String item = new String(b,n,2); 

              b2[n/2] = (byte)Integer.parseInt(item,16); 

            } 

        return b2; 

      }
      
      public static void main(String [] args){
    	  System.out.println(decrypt("4A924225874E5037"));
    	  System.out.println(encrypt("root"));
//    	  decode("utf-8","中国");
      }
}
